From: "Günther Noack" <gnoack@google.com>
To: "Mickaël Salaün" <mic@digikod.net>
Cc: Paul Moore <paul@paul-moore.com>,
"Serge E . Hallyn" <serge@hallyn.com>,
Konstantin Meskhidze <konstantin.meskhidze@huawei.com>,
Shervin Oloumi <enlightened@chromium.org>,
linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH v2 1/2] landlock: Extend documentation for kernel support
Date: Tue, 27 Feb 2024 17:32:20 +0100 [thread overview]
Message-ID: <Zd4OlL1G3t1D3TgC@google.com> (raw)
In-Reply-To: <20240227110550.3702236-1-mic@digikod.net>
On Tue, Feb 27, 2024 at 12:05:49PM +0100, Mickaël Salaün wrote:
> Extend the kernel support section with one subsection for build time
> configuration and another for boot time configuration.
>
> Extend the boot time subsection with a concrete example.
>
> Update the journalctl command to include the boot option.
>
> Cc: Günther Noack <gnoack@google.com>
> Cc: Kees Cook <keescook@chromium.org>
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> ---
>
> Changes since v1:
> * New patch, suggested by Kees Cook.
> ---
> Documentation/userspace-api/landlock.rst | 57 +++++++++++++++++++++---
> 1 file changed, 51 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst
> index 2e3822677061..838cc27db232 100644
> --- a/Documentation/userspace-api/landlock.rst
> +++ b/Documentation/userspace-api/landlock.rst
> +Boot time configuration
> +-----------------------
> +
> If the running kernel does not have ``landlock`` in ``CONFIG_LSM``, then we can
> -still enable it by adding ``lsm=landlock,[...]`` to
> +enable Landlock by adding ``lsm=landlock,[...]`` to
> Documentation/admin-guide/kernel-parameters.rst thanks to the bootloader
> configuration.
I would suggest: s/thanks to/in/
> +For example, if the current built-in configuration is:
> +
> +.. code-block:: console
> +
> + $ zgrep -h "^CONFIG_LSM=" "/boot/config-$(uname -r)" /proc/config.gz 2>/dev/null
> + CONFIG_LSM="lockdown,yama,integrity,apparmor"
> +
> +...and if the cmdline doesn't contain ``landlock`` either:
> +
> +.. code-block:: console
> +
> + $ sed -n 's/.*\(\<lsm=\S\+\).*/\1/p' /proc/cmdline
> + lsm=lockdown,yama,integrity,apparmor
> +
> +...we should configure the bootloader to set a cmdline extending the ``lsm``
> +list with the ``landlock,`` prefix::
Nit: Is the double colon at the end of this line accidental?
(It does not appear before the previous code block.)
> +
> + lsm=landlock,lockdown,yama,integrity,apparmor
> +
> +After a reboot, we can check that Landlock is up and running by looking at
> +kernel logs:
> +
> +.. code-block:: console
> +
> + # dmesg | grep landlock || journalctl -kb -g landlock
> + [ 0.000000] Command line: [...] lsm=landlock,lockdown,yama,integrity,apparmor
> + [ 0.000000] Kernel command line: [...] lsm=landlock,lockdown,yama,integrity,apparmor
> + [ 0.000000] LSM: initializing lsm=lockdown,capability,landlock,yama,integrity,apparmor
> + [ 0.000000] landlock: Up and running.
> +
> +Note that according to the built time kernel configuration,
s/built time/build time/
^
It feels like the phrase "according to" could be slightly more specific here.
To paraphrase Alejandro Colomar, "Note that" is usually redundant.
https://lore.kernel.org/all/0aafcdd6-4ac7-8501-c607-9a24a98597d7@gmail.com/
I'd suggest:
The kernel may be configured at build time to always load the ``lockdown`` and
``capability`` LSMs. In that case, these LSMs will appear at the beginning of
the ``LSM: initializing`` log line as well, even if they are not configured in
the boot loader.
> +``lockdown,capability,`` may always stay at the beginning of the ``LSM:
> +initializing lsm=`` list even if they are not configured with the bootloader,
Nit: The man pages spell this in two words as "boot loader".
> +which is OK.
> +
> +Network support
> +---------------
> +
> To be able to explicitly allow TCP operations (e.g., adding a network rule with
> ``LANDLOCK_ACCESS_NET_BIND_TCP``), the kernel must support TCP
> (``CONFIG_INET=y``). Otherwise, sys_landlock_add_rule() returns an
>
> base-commit: b4007fd27206c478a4b76e299bddf4a71787f520
> --
> 2.44.0
>
Reviewed-by: Günther Noack <gnoack@google.com>
next prev parent reply other threads:[~2024-02-27 16:32 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-27 11:05 [PATCH v2 1/2] landlock: Extend documentation for kernel support Mickaël Salaün
2024-02-27 11:05 ` [PATCH v2 2/2] landlock: Warn once if a Landlock action is requested while disabled Mickaël Salaün
2024-02-27 16:32 ` Günther Noack [this message]
2024-03-07 10:21 ` [PATCH v2 1/2] landlock: Extend documentation for kernel support Mickaël Salaün
2024-03-18 9:50 ` Alejandro Colomar
2024-03-19 10:46 ` Mickaël Salaün
2024-03-19 11:40 ` Alejandro Colomar
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